Study On Isolation Measure In Foundation Of Beijing Wansong Laoren Tower Induced By Vibrations Of Metro

Recently, with the large-scale development of Beijing Metro subway, the vibration when Metro train running is attracting universal attention of the society and people.The metro vibration not only affects people's daily life and work, and also affect nearby buildings. There are so many ancient buildings in Beijing urban district, and the age of these ancient buildings are so long, the superstructure and foundation are poor, so long-term vibration of Metro will affect the stability of these ancient buildings. Therefore, the measure of the vibration isolation and damping according to the Metro vibration has been to become an important research topic.In this dissertation, the continuous measures of barrier for isolation vibration which are taken in the foundation of Laoren tower nearby subway line 4 have been studied and analyzed. Using the measured rail base acceleration data to determine the vibration load which effect on the track bed, then through the finite element method to establish a two-dimensional calculation model plane which name is "tunnel-soil-foundation of tower" model plane, and then calculate the vibration response of the ground and tower foundation which without vibration isolation measures. By means of using the underground concrete continuous diaphragm wall, analysis the vibration isolation effect on the tower foundation of different depth and thickness of the barrier, then compare these data to find depth and thickness of the barrier which are suitable for Laoren tower foundation. Analysis the open ditch and a single material in different forms of isolation barrier effect, and then summed up the vibration-isolation behavior of each material. The result of study showed:1) Open ditch and the barriers of form, rubber and other materials have similar vibration-isolation effect, the effect on the attenuation of high frequency after 5Hz more well, while 0-5Hz low frequency vibration will be amplified; 2) With the improvement of the concrete strength grade, the isolation effect is not have significant change, but the 0-5Hz low frequency attenuation is better than the vibration-isolation of the open ditch and foam, rubber and other materials, and both within the 5-20Hz vibration amplification and attenuation are complementary, this establish the foundation of further analysis of the combination material barrier; 3) The main combinatorial material barriers include concrete hollow wall and concrete-rubber isolation wall, through the comparison, the vibration effect of the combinatorial isolation barriers is better than the single material isolation barriers, furthermore the combinatorial isolation barriers have the vibration behavior of each single material. In the comparison of the two combinatorial isolation barriers, the isolation effect of the concrete-rubber isolation wall is better than the concrete hollow wall, no matter in the attenuation of vibration displacement or in the attenuation of vibration acceleration.